Aspirin prevents preeclampsia and complications

Journal of Family Practice, Dec, 2003 by Susan M. Miller

Coomarasamy A, Honest H, Papaioannou S, Gee H, Khan KS. Aspirin for prevention of preeclampsia in women with historical risk factors: a systematic review. Obstet Gynecol 2003; 101:1319-1332.

* PRACTICE RECOMMENDATIONS

This meta-analysis shows that the use of aspirin in pregnant women predisposed to preeclampsia significantly reduces the rates of preeclampsia and perinatal death, without evidence of harm. A recent Cochrane review showed similar results. (1) It is reasonable to recommend low-dose aspirin therapy to women who have 1 or more risk factors for preeclampsia.

* BACKGROUND

Diabetes, renal disease, hypertension, and a personal or family history of preeclampsia confer a high risk of preeclampsia. Early identification and treatment of women prone to preeclampsia could reduce its risk and associated sequelae. Randomized trials evaluating aspirin's effectiveness for treating preeclampsia show a trend towards benefit, but most of these studies have been small.

* POPULATION STUDIED

This systematic review represents a total of 12,416 high-risk women. The studies included in this analysis represent women of various ages and used different criteria for defining women as high-risk.

* STUDY DESIGN AND VALIDITY

This was a meta-analysis of randomized trials that assessed aspirin's therapeutic benefit in women with historical risk factors for preeclampsia. The authors searched multiple electronic scientific databases (MEDLINE, EMBASE, Cochrane Library, National Research Register, SCISEARCH, and conference proceedings) and reference lists from primary and review articles to identify an exhaustive list of pertinent research. They contacted researchers to find unpublished studies.

After 729 citations were initially identified, 2 independent reviewers eliminated citations through screening of titles, abstracts, and manuscripts. Agreement was high between the 2 reviewers, but if necessary, a third independent reviewer resolved any disparity. Fourteen primary articles are included in this systematic review. A funnel plot demonstrated that publication or a related bias was unlikely.

The authors included studies in the meta-analysis if they were randomized trials. They compared low-dose aspirin (any definition) with placebo or no drug treatment, and the participants were women with risk factors for preeclampsia.

* OUTCOMES MEASURED

The primary outcomes in the majority of included studies were preeclampsia and perinatal death. Some studies reported other clinically relevant maternal or perinatal sequelae, such as preterm birth, birth weight, and antenatal bleeding or placental abruption.

* RESULTS

Treatment with aspirin, in doses ranging from 50 mg to 150 mg, started no earlier than at 12 weeks of pregnancy and continued, in most cases, until delivery. Fifty percent of the trials analyzed data based on an intention-to-treat protocol; the other trials failed to report this information. Follow-up for all 14 trials was >90%.

Pooled results from the studies demonstrated a significant reduction in both primary outcomes with aspirin usage. Odds ratios (OR) were 0.86 (95% confidence interval [CI], 0.76-0.96) and 0.79 (95% CI, 0.64-0.96) for preeclampsia and perinatal death, respectively. Analysis of other clinically relevant outcomes also proved the benefits of aspirin therapy. Spontaneous preterm births decreased (OR=0.86; 95% CI, 0.79-0.95) and the mean birth weight increased by a mean of 215 grams (95% CI, 90-341). Number of placental abruptions (0R=0.98; 95% CI, 0.79-1.21) and antepartum bleeding were similar with aspirin compared with placebo or no drug treatment.

REFERENCE

(1.) Knight M, Duley L, Henderson-Smart DJ, King JF. Antiplatelet agents for preventing and treating preeclampsia [systematic review]. Cochrane Database of Systematic Reviews 1, 2003.

Susan M. Miller, PharmD, BCPS, Cape Fear Valley Health System, Fayetteville, NC. E-mail: smiller@capefearvalley.com.